Stainless Steel Coil Tube — Industrial Coiled Tubing for Thermal Systems
Product Overview
The Stainless Steel Coil Tube (Coiltube) is a precision-engineered coiled tubular product manufactured by Wenzhou Jixing Metal Materials Co., Ltd. (Product No. 955). This product is specifically designed for integration into thermal energy distribution systems, including but not limited to greenhouse heating systems utilizing fan coil hot air supply configurations. The coil tube combines the inherent corrosion resistance and mechanical durability of stainless steel with the compact, space-efficient geometry of a continuous coil, making it an ideal heat exchange and fluid transport medium in controlled-environment agriculture, industrial process heating, and HVAC (Heating, Ventilation, and Air Conditioning) applications.
The coil tube is supplied as a continuous length of stainless steel tubing wound into a helical coil configuration, enabling efficient thermal transfer with minimal installation footprint. Its design facilitates seamless integration into fan coil units and convective heating loops, where hot air or fluid circulates through the coiled passages to deliver uniform thermal energy to the target environment.
Material & Properties
The coil tube is fabricated from high-grade austenitic stainless steel, selected for its superior combination of corrosion resistance, thermal conductivity, and mechanical integrity under cyclic thermal loading.
- Base Material: Austenitic Stainless Steel (commonly grades 304/06Cr19Ni10 or 316/06Cr17Ni12Mo2)
- Carbon (C) Content: ≤ 0.08 wt% (low-carbon variant to minimize sensitization risk)
- Chromium (Cr) Content: 18.0 – 20.0 wt% — provides passivation film stability
- Nickel (Ni) Content: 8.0 – 12.0 wt% — stabilizes austenitic crystal structure
- Molybdenum (Mo) Content: Up to 2.0 wt% (in 316 grade) — enhances pitting and crevice corrosion resistance
- Tensile Strength (UTS): ≥ 520 MPa (annealed condition)
- Yield Strength (0.2% Offset): ≥ 205 MPa
- Elongation at Break: ≥ 40%
- Thermal Conductivity: 14 – 16 W/(m·K) at 25 °C
- Operating Temperature Range: −196 °C to +870 °C (grade-dependent)
- Corrosion Resistance: Excellent resistance to atmospheric, aqueous, and mildly acidic environments; superior pitting resistance in chloride-containing media (316 grade)
- Magnetic Properties: Essentially non-magnetic (austenitic structure, relative permeability μr ≈ 1.02 – 1.05)
Specifications
| Parameter | Specification | Unit |
|---|---|---|
| Product Code | 955 | — |
| Product Name | Stainless Steel Coil Tube (Coiltube) | — |
| Outer Diameter (OD) | 6.0 – 50.8 (configurable) | mm |
| Wall Thickness (WT) | 0.5 – 3.0 (configurable) | mm |
| Coil Diameter (Center-to-Center) | 100 – 600 (configurable) | mm |
| Coil Pitch (Turn Spacing) | 2 – 20 (configurable) | mm |
| Coil Length (Total Uncoiled Length) | Up to 500 (configurable) | m |
| Surface Finish | Mirror Polish / Matte / Pickled & Passivated | — |
| End Condition | Plain / Threaded / Flanged / Custom | — |
| Maximum Working Pressure | Up to 1.6 (standard); up to 6.4 (reinforced) | MPa |
| Heat Transfer Coefficient | Up to 400 | W/(m²·K) |
| Standard | GB/T 14976, ASTM A269/A213, EN 10216-5 | — |
| Manufacturer | Wenzhou Jixing Metal Materials Co., Ltd. | — |
Manufacturing Process
The production of the Stainless Steel Coil Tube involves a multi-stage manufacturing sequence designed to ensure dimensional accuracy, metallurgical homogeneity, and surface integrity:
- Raw Material Preparation: High-purity stainless steel wire rod or seamless tubing stock is procured and subjected to incoming quality inspection, including chemical composition verification (Optical Emission Spectroscopy, OES) and mechanical property testing.
- Heat Treatment (Annealing): The tubing is solution-annealed at 1050 – 1150 °C followed by controlled cooling to restore full austenitic structure, relieve residual stresses, and achieve the desired soft and magnetic (SSM) or fully annealed condition.
- Precision Coiling: The tubing is fed through a CNC-controlled coiling head that winds the tube into a helical coil with tightly controlled coil diameter, pitch, and turn alignment. Tension and bending parameters are calibrated to prevent work hardening, ovalization, or surface defects at the coil bends.
- Welding & Joining (if applicable): Coil-to-coil or coil-to-straight transitions are accomplished via orbital TIG (Tungsten Inert Gas) welding under argon shielding, ensuring full-penetration welds with minimal heat-affected zone (HAZ) sensitization.
- Pickling & Passivation: The finished coil tube undergoes acid pickling (nitric/hydrofluoric acid blend) to remove surface oxides and scale, followed by passivation treatment to re-establish the protective chromium oxide passive film.
- Surface Finishing: Depending on application requirements, the tube may receive electropolishing, mechanical polishing, or brushing to achieve specified surface roughness (Ra ≤ 0.4 μm for mirror finish).
- Quality Inspection: Final inspection includes hydrostatic pressure testing, dimensional verification (OD, WT, coil geometry), visual surface examination, and optional destructive testing on sample coupons (tensile, impact, hardness).
Applications
The Stainless Steel Coil Tube is engineered for demanding thermal system applications, with demonstrated suitability in the following domains:
- Greenhouse Heating Systems: Integration into fan coil hot air supply systems for controlled-environment agriculture, where uniform and efficient heat distribution is critical for crop growth optimization. The coil tube's compact geometry maximizes heat exchange surface area within limited installation space, enabling precise thermal regulation of greenhouse microclimates.
- HVAC Heat Exchangers: Use as coil elements in air-handling units, radiators, and fan coil units for commercial and industrial building climate control.
- Process Heating & Cooling: Application in chemical processing, food and beverage industry, and pharmaceutical manufacturing where sanitary-grade fluid transport and heat exchange are required.
- Refrigeration & Chiller Systems: Deployment as evaporator or condenser coils in refrigeration loops, leveraging stainless steel's resistance to refrigerant-induced corrosion.
- Marine & Offshore Systems: Utilization in ballast water heating, engine room heat recovery, and desalination plant heat exchangers, where 316-grade coil tubes provide resistance to chloride-induced pitting.
- Geothermal & Solar Thermal Systems: Integration into ground-source heat exchangers and solar thermal collector manifolds for renewable energy applications.
Unique Selling Points
- Space-Efficient Thermal Geometry: The helical coil configuration provides a high heat transfer area-to-volume ratio, enabling compact installations in space-constrained environments such as greenhouses and industrial enclosures.
- Superior Corrosion & Fatigue Resistance: The austenitic stainless steel matrix resists cyclic thermal fatigue, chemical attack, and oxidative degradation, extending service life significantly beyond carbon steel alternatives.
- Sanitary & Hygienic Design: Smooth internal bore surface finish (electropolished option) prevents biofilm accumulation and facilitates CIP (Clean-In-Place) and SIP (Sterilize-In-Place) protocols, meeting FDA and 3-A sanitary standards.
- Customizable Configuration: Flexible manufacturing parameters (OD, WT, coil diameter, pitch, length) allow tailored solutions for specific thermal system designs.
- Environmental Sustainability: Stainless steel is 100% recyclable without degradation of material properties, aligning with circular economy principles and reducing lifecycle environmental impact.
Quality Certifications & Compliance
The Stainless Steel Coil Tube manufactured by Wenzhou Jixing Metal Materials Co., Ltd. adheres to internationally recognized quality management and product standards:
- ISO 9001:2015 — Quality Management Systems certification ensuring consistent manufacturing quality and process control.
- ISO 14001:2015 — Environmental Management Systems certification demonstrating commitment to sustainable production practices.
- GB/T 14976 — Chinese national standard for seamless stainless steel tubes for fluid transport, specifying chemical composition, mechanical properties, and dimensional tolerances.
- ASTM A269 / A269M — American standard for seamless austenitic stainless steel tubing, covering dimensions, chemical requirements, and heat treatment.
- EN 10216-5 — European standard for seamless stainless steel tubes for heat exchangers and similar applications.
- CE Marking — Conformity with European health, safety, and environmental protection standards.
- Mill Test Certificates (MTC) — Full third-party material certification (EN 10204 Type 3.1) provided with each batch, documenting chemical analysis, mechanical test results, and heat treatment records.
Note: All specifications listed above are typical values and may vary based on specific order requirements. Custom configurations are available upon request. Prospective buyers are advised to consult Wenzhou Jixing Metal Materials Co., Ltd. directly for application-specific engineering support and detailed performance data sheets.